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Study: Boreal forests burning at unprecedented rate

FAIRBANKS, (AP) — The world’s boreal forests, which stretch from interior Alaska to the Atlantic Ocean and span regions of Russia and Scandinavia, are burning at a rate considered historically unprecedented, according to a new study of the Yukon Flats region.

The study was published last week in the Proceedings of the National Academy of the Sciences.

Both fire frequency and the amount of biomass burned are higher now than they’ve been in the past 10,000 years, according to researchers. And the length of the fire season and the intensity of the fires have increased in just the past decade, said state forester Chris Maisch, director of the Alaska Division of Forestry.

“We’re observing change,” Maisch said. “There’s no doubt about it.”

People in Alaska’s interior have been increasingly inundated with smoke from wildfires, which can cause and aggravate respiratory problems.

The start of the statutory fire season used to be May 1. However, in 2006 the state was forced to move that start up by a month.

Researchers in the Yukon Flats sampled charcoal records from 14 lakes to infer burning during most of the Holocene epoch. That’s a geologic time frame stretching to the present from about 11,700 years ago.

Researchers combined the data with observational records of the past six decades to come up with their findings. Before the present, the highest biomass burning took place about 800 years ago during the period called the Medieval Climate Anomaly. A great amount of biomass burned during this period but researchers say fire frequency was relatively low.

The new study’s lead author, Ryan Kelly, said researchers believe this was in part because the forest consisted of less combustible deciduous trees. Following forest fires, deciduous trees tend to move in to heavily burned areas.

Researchers say that if global temperatures continue to warm, areas such as the Yukon Flats may not slow down even with less combustible makeup.

“Many studies (usually based on models) have predicted that fire frequency, fire severity and/or area burned will rise dramatically over the coming century,” Kelly said. “Given that most of our study area has burned recently already, it seems like this would require deciduous forest stands to burn more than they do at present, and some studies have suggested that will in fact happen.”

Kelly predicts that increased fire activity in interior Alaska would lead to the forest makeup shifting from coniferous species, such as black spruce, to deciduous species like birch and aspen.